wireless control system and method in an illumination network

ABSTRACT

The present invention proposes a wireless control system and method which may be mainly used in illumination networks. The wireless control system and method of the invention distributes data signals to be transmitted at a control terminal in different time slots of different frequencies for transmission, while each node in the system will only receive its corresponding data signal in a predetermined time slot of a predetermined frequency. Thus a high operating rate can be obtained at the control terminal while maintaining the operating rate of the node unchanged. This helps to greatly reduce the cost of the wireless transceiver of each node, thereby correspondingly reducing the cost of the whole system and realizing a high expansibility.

TECHNICAL FIELD

The present invention relates to a wireless control technique, inparticular to a wireless control system and method for use in anillumination network.

BACKGROUND ART

Centrally controlled illumination networks are being widely usedrecently, such a control mode allowing the user to control theillumination networks in real time to display different illuminationprofiles. A main feature of a control system using such a control modeis that the data rates for communication between a console and nodes areasymmetrical, because generally there is only one or a few consoles,comparing to a large number of nodes (thousands or even tens ofthousands).

Traditionally, the console and the nodes are connected via cables, andsuch connection may bring many engineering difficulties and troubles tothe system in its installation, commissioning and maintenance. With thedevelopment of the wireless communication technique, people began toexplore whether a wireless connection can be used to replace the cableso as to eliminate the difficulties and troubles brought about by thewired connection. Although the wireless control system is veryattractive, it still has many pending problems concerning display whenbeing applied to an illumination network, for example, the data rate,the communication distance, the cost control and the time needed forcommercializing, etc. Theoretically, a brand new wireless control systemcan be developed specially for the illumination networks, but the highcost and the long time for commercializing will hinder thepopularization and application of such a new system.

Therefore, it would be currently a relatively better solution to fullyuse the existing wireless network protocols. However, the existingwireless network protocols have some serious problems when beingdirectly applied to illumination networks, especially large-scaleillumination networks.

Taking an illumination network having one console and 10,000 nodes as anexample, it can be supposed that each node comprises a wirelesstransceiver and 3 colourful (red/green/blue) lamps, the illuminationnetwork consisting of said 10,000 nodes forms a screen, which can beused to display video or static images. When video needs to bedisplayed, each lamp may wirelessly receive 8 bit data from the consolewithin 1/25 second, so an average data rate of a receiver of each nodeis 8*25*3 bps=600 bps (bit/second); but for a transmitter of theconsole, its total data rate will be 600*10000 bps=6 Mbps. On thecontrary, a transmitter of the node and a receiver of the console onlyoperate occasionally and they transmit information at a very low rate.

Obviously, with respect to such an illumination system mentioned above,the required wireless control could be implemented by either a TDMA(Time Division Multiple Access) system supporting a data rate exceeding6 Mbps, or an FDMA (Frequency Division Multiple Access) system havingmore than 10000 frequency channels. However, the TDMA system that cansupport a data rate exceeding 6 Mbps is too expensive to be suitable foruse in such an application, and in practice there is no FDMA system thatcan simultaneously support 10,000 channels with each channel operatingat 600 bps at present, and customizing such FDMA systems to differentillumination networks will require a long developing period and a highcost. In addition, expansibility of the TDMA and FDMA systems is verylimited.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a hybrid wirelesscontrol system and method, in which data signals are transmitted in away incorporating characteristics of both TDMA and FDMA, thus a higheroperation rate can be obtained at the control terminal while keeping theoperation rate of the nodes unchanged.

A wireless control system according to the present invention, whichcomprises:

a console, comprising a plurality of central wireless devicesrespectively operating at different frequencies to transmit data signalsof different contents; and

a plurality of nodes each comprising a terminal wireless device forreceiving, at a corresponding frequency, the data signal from a centralwireless device corresponding to said frequency, and all the terminalwireless devices corresponding to said frequency respectively operatingin different time slots of said frequency channel.

A wireless control method according to the present invention, whichcomprises steps of

a. dividing a data signal to be transmitted into a plurality ofdifferent sub-signals;

b. grouping said plurality of sub-signals into a plurality of groups tobe transmitted at different frequencies; and

c. transmitting a group of sub-signals that are transmitted at the samefrequency to different receiving terminals in different time slots.

In the wireless control system and method of the present invention, theconsole distributes the data signals to be transmitted in different timeslots of different frequencies, and each node will receive itscorresponding data signal only in a predetermined time slot of apredetermined frequency. Therefore, while maintaining the low receivingrate of the wireless transceiver at each node, the console can stilltransmit high rate data signals to a plurality of nodes in real time,respectively. This helps to greatly reduce the cost of the wirelesstransceiver at each node, thereby reducing the cost of the whole systemaccordingly. In addition, during practical application, by adjusting thenumber of frequencies used or the number of time slots at eachfrequency, said wireless control system can be adapted to illuminationnetworks of different scales, thus acquiring a high expansibility.

Other objects and effects of the invention will become more apparent andeasily appreciated by referring to the following description taken inconjunction with the accompanying drawings and the claims and with abetter understanding of the invention.

DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail below withreference to the drawings, wherein

FIG. 1 is a schematic drawing of the structure of the illuminationnetwork using the wireless control system of the present invention;

FIG. 2 is a schematic drawing of the wireless control system accordingto a first embodiment of the present invention;

FIG. 3 is a schematic drawing of the wireless control system accordingto a second embodiment of the present invention; and

FIG. 4 is a schematic drawing of the wireless control system accordingto a third embodiment of the present invention.

Throughout the drawings, the same reference numerals indicate similar orcorresponding features or functions.

PREFERRED EMBODIMENT

The previously mentioned illumination network comprising one console and10,000 nodes is still used herein as an example to illustrate in detailthe operating principle of the wireless control system of the presentinvention when it is applied to the illumination network.

Referring to FIG. 1, the illumination network comprises a console 10 anda screen 20 formed of 10,000 nodes 30. The console 10 can transmit datasignals to each node 30 to respectively control changes of itsbrightness and color, thereby making the screen 20 to displaycorresponding profiles. Each node 30 comprises a wireless transceiver 31and three lamps L_(R), L_(G) and L_(B) of red, green and blue. Thebrightness of said three lamps is controlled by a 24-bit signal receivedby the wireless transceiver 31.

The wireless control system of the present invention is mainly used forestablishing a wireless connection between the console 10 and the nodes30 in the illumination network, so that the console 10 can correctlycontrol the screen 20 to display the desired content. Since each node 30has a wireless transceiver 31, the cost of the whole system is largelydetermined by the cost of each wireless transceiver.

The structure of the wireless control system of the present invention isas shown in FIG. 2, which uses a hybrid transmission scheme thatincorporates the characteristics of the TDMA and FDMA systems, and canoperate both in a broadcast mode and in a TDD (Time Division Duplex)mode.

The console 10 has M central wireless transceivers TRx1˜TRxM, and thenodes 30 have M*N=10,000 terminal wireless transceivers 31. The Mcentral wireless transceivers TRx1˜TRxM of the console 10 respectivelyoperate in M different carrier frequencies f₁, f₂, . . . , f_(m), butthey are synchronous in respect of data transceiving. All the centralwireless transceivers TRx1˜TRxM operate consecutively in time. Given theoperation rate of each central wireless transceiver is R, the maximumrate that can be reached by the console 10 is R_(C), wherein R_(C)=M*R.

During system operation, each node 30 performs the corresponding displayaccording to the signal received from the console, and the console needsto transmit different contents to the total M*N nodes 30 in real time,so the wireless channel of the console 10 is divided into M*Nsub-channels. An easy way to implement is to first divide the wirelesschannel according to the frequency, then divide each frequencysub-channel according to the time slot. As shown in FIG. 2, theembodiment includes M frequency sub-channels, each being divided into Ntime slots, thus there are M*N sub-channels. Each central wirelesstransceiver operates in a fixed frequency sub-channel and communicateswith N terminal wireless transceivers 31, while the terminal wirelesstransceiver 31 of each node 30 operates in a fixed time slot of a fixedfrequency sub-channel. Although the contents transmitted in these M*Nsub-channels diverse from each other, the console 10 maintains thesynchronization in time, thus ensuring that the screen 20 could displaythe correct video or images.

In a broadcast mode, the console 10 first divides the video or image ofeach frame into M*N units of data signals, then transmits said M*N unitsof data signals to the corresponding nodes 30 via the M*N sub-channels.As shown in FIG. 2, each grid represents one unit of data signals,wherein Ch_(Nm) represents a corresponding sub-channel, and TR_(Nm)represents the wireless transceiver of a corresponding node.

When the screen 20 is displaying a static or pseudo-static image, thedisplay is updated slowly, for example 5 frames/second. At this time,the downlink, i.e. the direction from the console 10 to the nodes 30,requires a very low data rate, so many frames have idle time slots whichcan be used as the uplink channel to transmit the feedback signalsgenerated by nodes 30. As shown in FIG. 3, the uplink and downlink mayalternately transmit frame signals so as to realize duplexcommunication. Since the requirement on the display precision whendisplaying static images is higher than when displaying dynamic video,the significance of using the duplex communication herein is that it canimprove the reliability of data transmission.

Signals in the uplink need also be synchronous in time. But it isrelatively difficult to maintain precise synchronization in the uplinkbecause the transceivers of the respective nodes have different responsetime. In practice, this problem may be alleviated by using repeatedcoding in the uplink channel, meanwhile, since the feedback signals inthe uplink only include very few bits as compared to the downlink, thismethod is feasible. In addition, since the entire data rate is low, theFEC (Forward Error Correction) can be used in both the uplink and thedownlink to further improve the reliability of data transmission.

In some wireless communication protocols, such as ZigBee, when thewireless transceiver operates in different frequency bands, it hasdifferent data rates. In this case, the number of time slots dividedvaries in different frequency sub-channels. As shown in FIG. 4, thewireless transceiver operating at the M^(th) frequency is at a low datarate, so the number of time slots in the M^(th) frequency sub-channel isless than that in other frequency sub-channels.

It can be seen from the above embodiments that in the broadcast mode ofthe present invention, although the receiving rate of the wirelesstransceiver at each node is very low, the console can still transmithigh rate data signals respectively to a plurality of nodes in realtime. This helps to greatly reduce the cost of the wireless transceiverof each node, thereby reducing the cost of the whole system accordingly.Furthermore, the wireless transceivers of the nodes operating at a lowrate also helps to increase the communication distance.

In the duplex mode, the communication between the console and the nodescan be made more reliable by means of the feedback information of thenodes and FEC, etc.

Another important feature of the wireless control system of the presentinvention is its full expansibility. In practical use, the wirelesscontrol system can be adapted to illumination networks of differentscales by correspondingly adjusting the value of M or N.

Although the wireless control system in the embodiments of the presentinvention is used to control illumination networks, it is obvious thatsuch a wireless control system can also be used in other circumstanceswhere a lot of nodes need to be controlled in real time.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art shallunderstand that various improvements can be made to the wireless controlsystem and method as disclosed in this invention without departing fromthe contents of the present invention and the protection scope of theappended claims. Therefore, the protection scope of the invention shallbe determined by the appended claims. In addition, any reference signsused in the claims shall not be construed as limiting the protectionscope of the claims.

1. A wireless control system, comprising: a console, comprising aplurality of central wireless devices respectively operating atdifferent frequencies to transmit data signals of different contents;and a plurality of nodes each comprising a terminal wireless device forreceiving, at a corresponding frequency, the data signal from a centralwireless device corresponding to said frequency, and all the terminalwireless devices corresponding to said frequency respectively operatingin different time slots of said frequency channel, wherein: each of thenodes further includes at least one lamp and each node performs adisplay according to the data signal received by the terminal wirelessdevice thereof; the data signals of different contents are capable offorming frame data signals of a video or a static image to control amatrix or screen formed by the lamps of the nodes to display thecorresponding video or static image; and the console divides the framedata signals into data signals of different contents according todifferent positions of the lamps of the nodes, and that each divideddata signal is transmitted by a predetermined central wireless device ina predetermined time slot of the operating frequency thereof, so thateach divided data signal will be received by only one correspondingnode. 2-4. (canceled)
 5. The system according to claim 1, wherein theterminal wireless device and the central wireless device are bothwireless transceivers.
 6. The system according to claim 5, whereinamount of the terminal wireless devices is greater than that of thecentral wireless devices.
 7. The system according to claim 6, whereinthe amount of the terminal wireless devices equals to a sum of amountsof time slots at all operating frequencies.
 8. The system according toclaim 5, wherein the central wireless device is also used to receivefeedback signals from the nodes.
 9. The system according to claim 8,wherein the terminal wireless device of the node transmits the feedbacksignals in a time slot of an idle frame of the system.
 10. A wirelesscontrol method, which comprises steps of: (a) dividing a data signal tobe transmitted into a plurality of different sub-signals; (b) groupingsaid plurality of sub-signals into a plurality of groups to betransmitted at different frequencies; and (c) transmitting a group ofsub-signals that are to be transmitted at the same frequency todifferent receiving terminals in different time slots, wherein: each ofthe receiving terminals includes at least one lamp, and each of thereceiving terminals controls the at least one lamp according to thereceived sub-signal; the data signal is a frame data signal of a videoor a static image to control a matrix or screen formed by the lamps ofthe receiving terminals to display a corresponding video or staticimage; and the step (a) includes a sub-step of dividing the frame datasignal into a plurality of different sub-signals according to differentpositions of the lamps of the receiving terminals. 11-13. (canceled) 14.The method according to claim 10, wherein each of the receivingterminals operates in a predetermined time slot of a predeterminedfrequency, so that each of the receiving terminals receives only onecorresponding sub-signal.
 15. The method according to claim 10, furthercomprising a step of d. receiving feedback signals from differentreceiving terminals.